Werna, I don't believe in volcanic hypothesis of Antarctic ice melting by the same way, like you. From your map it's evident, the glaciers are melting in contact with ocean predominantly. But the volcanic hypothesis can be used for explanation of isolated glaciers melting, like the Ilulissat one.

http://www.iht.com/articles/2008/01/20/europe/climate.php

It should be pointed out, from global warming perspective isn't relevant, whether the glaciers are melting with the increased speed, or just subliming (at higher altitudes) - the origin is supposedly the same in both cases: unbalanced heat flux equilibrium.